In recent years, in active-matrix-type liquid crystal display devices including switching elements in respective pixels, a structure mainly using a vertical electric field, such as a vertical aligned mode, has been put to practical use. In such a liquid crystal display device of a vertical electric field mode, liquid crystal molecules are switched by a vertical electric field which is produced between a pixel electrode formed on an array substrate and a common electrode formed on a counter-substrate.
In the meantime, in the liquid crystal display device, an alignment film is required in order to uniformize alignment directions of liquid crystal molecules in a state in which no voltage is applied to a liquid crystal layer. In general, an alignment film is formed by using an organic material such as polyimide. In recent years, however, there has been proposed a technique of forming the alignment film by an inorganic material such as silicon dioxide (SiO2).